CASE STUDY

Enhancing Conveyor Safety at Hindustan Zinc Through HAZOP Methodology

Overview

  • Hindustan Zinc is India’s largest and the world’s second largest producer of zinc alloys.
  • With over 50 years of experience, HZL prioritize the safety of their people and conserve scarce resources through technology and innovation.
  • Lead-zinc mines, lead smelters, hydrometallurgical zinc smelters, pyrometallurgical lead-zinc smelters, sulfuric acid, and closed-circuit power plants in northern India are among the activities of Hindustan Zinc.
  • Total metal production capacity is 1,123 tonnes.
  • These fields include Zawar Group of Mines, Rajpura Dariba Mine, Sindesar Khurd Mine, Rampura Agucha Mine and Kayad Mine

What is HAZOP?

The Hazard and Operability (HAZOP) Study is a methodical and organized evaluation of complex systems, like process facilities, aimed at identifying hazards that could pose risks to personnel, equipment, the environment, and system operability.

In the process safety industry, HAZOP is regarded as a key tool for identifying potential hazards.

Scope of the HAZOP Study

The scope of this HAZOP study includes assessing the pipe conveyor system used for transporting tailings, ensuring the design complies with safety regulations, and identifying any operational deficiencies. The goal is to prevent hazardous incidents such as blockages, spillages, or metal contamination.

HAZOP METHODOLOGY

Key Terms in HAZOP Methodology

  1. Node: A defined point in the process, represented on the P&ID, where deviations are analyzed.
  2. Design Intent: The desired operational state of a node.
  3. Deviation: Any departure from the intended operational state.
  4. Guidewords: Terms like “more,” “less,” or “reverse” used to identify potential hazards.
  5. Cause: Why a deviation might occur.
  6. Consequence: The impact of such deviations.
  7. Safety Measures: Controls in place to mitigate or prevent hazards.
  8. Actions: Recommendations to improve safety.
The image is a flowchart depicting the process of conducting a HAZOP (Hazard and Operability) Study. It starts with an explanation of the overall design, followed by selecting a node, agreeing on the design intent, and identifying relevant elements. The flowchart then guides users to select elements and characteristics, apply guide words, and assess deviations. If a deviation is deemed credible, the causes, consequences, and protections are investigated and documented. The process continues until all guide words and elements have been thoroughly examined, ending when all parts have been reviewed.

Challenges Encounterd

  • System Complexity: The detailed pipe conveyor system, including components such as flap gates, surge hoppers, and magnetic separators, presents challenges in identifying all potential hazards and operability issues. Each component brings its own unique risks that require thorough evaluation.
  • Data Availability: Comprehensive and accurate data is essential; lacking or outdated information can impede hazard identification.
  • Focus: Limiting the HAZOP study to safety and environmental concerns can result in an incomplete risk assessment.
  • Bypass Management: Managing bypasses, such as manual operation, introduces additional risks that require proper control.
  • Technological Integration: Incorporating new technologies into the HAZOP study is complex and necessitates thorough hazard evaluation.
  • Blockages and Spillage: Accumulation of material in the surge hopper or pipe conveyor can cause blockages and spills.
  •  Metal Contamination: Ineffective performance of the belt magnetic separator or metal detector can lead to metal contamination
  • Control System Malfunction: Failures in the software or hardware of the monitoring and control system can disrupt operations.

Recomendations

Identify Potential Hazards

  • Blockages in the pipe conveyor can cause overflow or spillage of tailings, posing operational and environmental risks.
  • Metal contamination is a potential hazard if the magnetic separator fails, allowing metal to mix with the tailings. Equipment failures, such as malfunctions in the belt weigh feeder or flap gate, can disrupt the process.

Analyze Causes and Consequences

  • Blockages may result from oversized particles or material buildup within the conveyor system.
  • Metal contamination can occur due to a malfunctioning magnetic separator, compromising tailings quality.
  • Equipment failures might arise from wear and tear, insufficient maintenance, or operational errors, leading to downtime and safety hazards.

Propose Mitigation Measures

  • Regular maintenance and inspections should be scheduled to ensure all equipment functions correctly.
  • Installing redundant systems for critical components like the magnetic separator and weigh feeder can provide backups.

Implement Control Measures

  • Automated controls can manage the flow of tailings and detect anomalies, enhancing system reliability.
  • Safety interlocks should be installed to shut down the system if a hazard is detected, preventing further issues.
  • Periodic training and awareness programs hosted for staff on operating procedures.

Conclusion

This HAZOP study of Hindustan Zinc’s pipe conveyor system ensured the identification of potential hazards and operational inefficiencies, contributing to improved safety and process reliability. By implementing the proposed mitigation and control measures, HZL can minimize operational risks and enhance safety performance.